The invention relates to magnetic refrigeration and more particularly to low temperature refrigeration between about 4 and about 20 K., with an apparatus and method utilizing a belt of magnetic material passed in and out of a magnetic field with heat exchangers within and outside the field operably disposed to accomplish refrigeration.
Magnetic refrigerators such as disclosed in U.S. Pat. No. 4,332,135 to Barclay et al. approximating cycles such as Brayton, Carnot, Ericsson, and Stirling cycles are known. Such magnetic refrigerators generally utilize paramagnetic or ferromagnetic material and move it in and out of a magnetic field to magnetize and demagnetize it in some manner. Materials capable of use in such refrigerators are disclosed in the '135 patent; many such magnetic refrigeration devices are operable over wide temperature ranges by staging a plurality of materials. Wheel type magnetic refrigerators such as disclosed in U.S. Pat. No. 4,408,463, to Barclay are also known. Wheel-type refrigerators are operable over various temperature ranges utilizing magnetic materials such as disclosed in the '135 patent.
There is, however, an existing need for an efficient refrigeration apparatus and method to refrigerate from about 20 to about 4 K. The instant invention provides an apparatus and method capable of efficiently refrigerating over this temperature range.
One object of the present invention is to refrigerate over a range of from about 20 to about 4 K.
Another object of the present invention is to provide highly efficient refrigeration.
One advantage of the instant invention is that an apparatus in accordance therewith requires little or no maintenance for extended periods of time because it is simple in design, has few moving parts and does not require periodic lubrication or adjustments.
Another advantage of the instant invention is that an apparatus in accordance therewith can be operated at various speeds to accomodate various refrigeration loads.